Can't bleed the linked brake


Information and questions on GL1200 Goldwings (1984-1987)
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Goofaroo
Posts: 155
Joined: Mon Jan 16, 2017 7:42 pm
Location: Guthrie, OK
Motorcycle: 1986 GL1200 Aspencade
2004 Kawasaki Concours
1978 BMW R100S
1971 Honda CB500/4
2007 Kawasaki KLR650
2002 Kawasaki KLR250
1992 Kawasaki KDX200
1987 Kawasaki KDX200
1985 Honda XR350R
1971 Honda CT90
1984 Honda NH125 Aero
2008 Yamaha Vino 125

Can't bleed the linked brake

Post by Goofaroo »



I have rebuilt the calipers and master cylinder and installed new hoses. I have now invested about 8 hours and $30 worth of brake fluid and I have nothing. The brake pedal feels like it has nothing but air in the m/c. I am using a floor standing mighty vac. So far I have repeatedly done the following:

Bled the front system until it appears to be bubble free, then the same for the rear.

Teed off of my vacuum and bled both calipers simultaneously.

Tried the above while working the pedal.

Tried priming the m/c. It is moving fluid.

Tried tapping on everything and wiggling hoses while vacuuming.

Tried using a syringe to force fluid in from the caliper.

Made a cover for the m/c so that I could hook up the vacuum and reverse bleed the system.

I'm at a loss at this point. No matter what I do I get the same result. I have read as much as I could online but most threads either end without resolution or are resolved by things that I have tried repeatedly. I am VERY interested in any information that might keep me from having to bury this motorcycle in the backyard where it can cause no further grief.
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User avatar
Rednaxs60
Posts: 2347
Joined: Wed Nov 18, 2015 12:44 pm
Location: Victoria, British Columbia, Canada
Motorcycle: 1985 GL1200 LTD
1995 GL1500 SE CDN Edition
2012 Suzuki DL1000 VStrom
2008 GL1800 (sold)
Ontario 1985 GL1200 LTD (sold)

Re: Can't bleed the linked brake

Post by Rednaxs60 »

Rebuilt the calipers on my '85 LTD; however, did not rebuild the MCs. Did rebuild the clutch MC and it is slightly different than before I did the rebuild - even put in two rebuild kits to see if it would be as before the rebuild, not the same but very close - still bugs me. Mention this because I understand how frustrating something can be.

Are the caliper pistons in the right way? OEM manual details to install the pistons with the dished ends towards the pads. Probably a simple question, but stranger things have happened. Other than this, the MC controls the pressure to the calipers. If you have no air in the system, there has to be something with the MC that is not quite right.

When I was learning about cars in my father's service station many years ago, and I was taught about rebuilding MCs, I was told to always pre-bleed the MC before install. This removed the air from the MC. Maybe not quite so simple with a bike MC, but something to consider.

Just my thoughts on your issue. Good luck.
"When you write the story of your life, don't let anyone else hold the pen"

Ernest

User avatar
Goofaroo
Posts: 155
Joined: Mon Jan 16, 2017 7:42 pm
Location: Guthrie, OK
Motorcycle: 1986 GL1200 Aspencade
2004 Kawasaki Concours
1978 BMW R100S
1971 Honda CB500/4
2007 Kawasaki KLR650
2002 Kawasaki KLR250
1992 Kawasaki KDX200
1987 Kawasaki KDX200
1985 Honda XR350R
1971 Honda CT90
1984 Honda NH125 Aero
2008 Yamaha Vino 125

Re: Can't bleed the linked brake

Post by Goofaroo »

Thanks for the reply. I definitely assembled the calipers properly so unfortunately the fix won't be as simple as turning the pistons around. I have air in the system that just won't budge. I've been stewing over this all day and I'm really not sure what to do but I'm considering pulling the m/c back off tomorrow and bench bleed it thoroughly and see if I can get anything different to happen. So far my dislike of the linked brake system has been escalating. It's already a nuisance and I haven't even tried it yet. lol

User avatar
Rednaxs60
Posts: 2347
Joined: Wed Nov 18, 2015 12:44 pm
Location: Victoria, British Columbia, Canada
Motorcycle: 1985 GL1200 LTD
1995 GL1500 SE CDN Edition
2012 Suzuki DL1000 VStrom
2008 GL1800 (sold)
Ontario 1985 GL1200 LTD (sold)

Re: Can't bleed the linked brake

Post by Rednaxs60 »

The linked system on these older GWs is relatively simple compared to the 1800 system that has servos and such. I also think some of the sport and touring models of Honda and other manufacturers makes these brakes extremely simplistic.

I have a rebuild kit for my 85, but have not wanted to tackle it - too much down time. What kit did you get? Mine is a K&L Kit made in Japan. Got it from Canada's motorcycle (now called Fortnine).

I did replace the OEM lines with SS Teflon lines - brakes and clutch. So far everything is working well. I'm now waiting until I get my second '85 LTD out here from my brother's place before I tackle more rebuilding. Want to have one bike on the road at all times.

Look forward to hearing how it goes.

Best of luck.
"When you write the story of your life, don't let anyone else hold the pen"

Ernest

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oldishwinger
Posts: 414
Joined: Sun Jul 14, 2013 11:26 pm
Location: New Zealand
Motorcycle: 1986 GL1200 Aspencade

Re: Can't bleed the linked brake

Post by oldishwinger »

they can be devil to air out them particularity after a rebuild, tried bleeding by increments? it can get a bit messy, undo the hose from the front caliper, might like to place end in a bottle or something, press the pedal gently to get an air free flow. replace the hose on the caliper, and completely unscrew the bleed screw and again press the pedal gently (several times if required) to get an air free flow. cover the tire etc, from any oil fall out.

replace the bleed screw, tighten and check the pedal, if its still rubbish bleed the front normally.

same procedure with the rear if needed.

I did this when I replaced a slave cylinder on the clutch, and could not get air out by conventional means and it worked. good luck

User avatar
Goofaroo
Posts: 155
Joined: Mon Jan 16, 2017 7:42 pm
Location: Guthrie, OK
Motorcycle: 1986 GL1200 Aspencade
2004 Kawasaki Concours
1978 BMW R100S
1971 Honda CB500/4
2007 Kawasaki KLR650
2002 Kawasaki KLR250
1992 Kawasaki KDX200
1987 Kawasaki KDX200
1985 Honda XR350R
1971 Honda CT90
1984 Honda NH125 Aero
2008 Yamaha Vino 125

Re: Can't bleed the linked brake

Post by Goofaroo »

I am now officially THE expert on bleeding the linked system on GL1200s. To earn that status I have run $45 worth of brake fluid through the system in every means possible. I can reverse bleed (vacuum or pressure) this bike in my sleep by more than one method. I know things about bleeding this brake system that would make Soichiro Honda envious.

My shop is trashed. I made a helluva mess with the brake fluid and I'm going to have to clean myself up with diesel fuel in the shower but I finally have brakes. It turns out that if you put the spring in the m/c first followed by the cup and the piston it takes approximately 4 minutes to bleed this system and about $1.12 worth of brake fluid. I bench bled the M/C and vacuum bled the front then the rear. Three or four pumps of the pedal and it was firm with nice feel and is holding steady. I'm rolling it outside tomorrow for a good scrubbing. Then I just need to install the left bag, seat, and running boards and I'll take it for a spin. Everything up front went together beautifully. I really tidied up the wiring and the cables in the steering well and everything is nice and solid throughout the fairing and dummy tank. All controls and switches are cleaned and greased. The brake pedal pivot was greased and I have the angle set up. The new steering head bearings feel great and my initial measurement shows a sag of around 28mm and I was shooting for 30-35 but I need to go ride it to let it settle in and then check it again. I can't wait to try these brakes.

I can't believe I put the m/c together wrong but that led to my legendary status among the brake bleeder crowd. I will never have trouble bleeding a brake system for the rest of my life. Which is nice. lol

User avatar
Rednaxs60
Posts: 2347
Joined: Wed Nov 18, 2015 12:44 pm
Location: Victoria, British Columbia, Canada
Motorcycle: 1985 GL1200 LTD
1995 GL1500 SE CDN Edition
2012 Suzuki DL1000 VStrom
2008 GL1800 (sold)
Ontario 1985 GL1200 LTD (sold)

Re: Can't bleed the linked brake

Post by Rednaxs60 »

Love it when a plan comes together. You are going to be surprised at how these brakes work.

Going to wait until I get a smallish ultrasonic cleaner to do my rear MC. Going to let my siblings know what I want for my birthday and exactly what it is to get. Not holding my breath, but worth a try.

The other item I installed on the calipers and clutch slave were Speed Bleeders. Makes flushing real easy for one person.

Cheers


"When you write the story of your life, don't let anyone else hold the pen"

Ernest

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